Poly(vinylalkylether)-containing hot-melt adhesives for polyethylene and polypropylene

ABSTRACT

Hot-melt adhesives based upon a mixture composed of poly(vinylmethylether), greater than about 10 weight percent of a thermoplastic resin and, optionally a tackifier resin and/or extender, are found to be superior for the binding of polyolefins such as polyethylene, polypropylene, and ethylene-propylene copolymers to themselves and to other substrates. In particular, the hot-melt adhesives are useful for bonding polyethylene-backed and latex-backed carpet to polyethylene, polypropylene, or ethylene-propylene copolymer.

This application is a continuation-in-part of U.S. Ser. No. 292,413,filed Dec. 30, 1988.

BACKGROUND OF THE INVENTION

This invention relates to improved hot-melt adhesive compositionseffective in binding polyolefins to themselves and to other materialswhich are based upon a poly(vinylalkylether) and, more particularly, tohot-melt adhesive compositions which strongly bind polyolefins, inparticular polyethylene, polypropylene, and ethylene-propylenecopolymers, to themselves and other substrates, and which are formulatedfrom a poly(vinylmethylether), a thermoplastic resin, and optionally, atackifier resin.

Hot-melt adhesives produce a bond between two materials by cooling ofthe molten adhesive which is applied to the materials in a melted state.They are distinguishable from those products which require crosslinkingor other chemical reactions to achieve ultimate bond strength and fromthose materials that require loss of solvent or water to achieve thebond strength. Prior to heating, the hot-melt adhesives are solids thatcan be provided in bulk or in pelletized or rod form for ease ofhandling. Upon heating, the hot-melt adhesive composition melts rathersharply and flows readily for application to a substrate. Since hot-meltadhesives are thermoplastic rather than thermosetting, and are thusremeltable they can be applied to a first substrate and later remeltedto form a hot-melt bond with a second substrate. Hot-melt adhesives canhave considerable advantage over other types of adhesives for a numberof uses and have a significant commercial importance.

There are a variety of uses for hot-melt adhesives which are out in themarket place. However, while one hot-melt adhesive may be used forbonding in a particular use or application, the same adhesive may becompletely unsuitable for other uses or applications. While manysatisfactory hot-melt adhesives are available to the art, the art isconstantly seeking new compositions having superior performance, lowercost, and/or stronger bonding of the substrate.

Polyethylene, polypropylene, and ethylene-propylene copolymers arewidely used in many applications which require adhering these plasticsto themselves as well as to other materials. However, adhesives do notform strong bonds to untreated polyolefin surfaces. The difficultiesencountered in developing adequate adhesion to polyethylene andpolypropylene can be attributed in large part to the non-porous andnon-polar characteristics of these materials. In addition, the presenceof surface materials such as mold release agents, slip agents,antioxidants, polymerization impurities, and low-molecular-weight,surface polymer further deteriorates surface conditions for adhesion.Various surface preparation procedures, including etching with sodiumdichromate-sulfuric acid solution, treating with flame, coronadischarge, electron beam, laser light, ultraviolet radiation, hotchlorinated solvent, and applying chemically reactive primers have beendeveloped to afford a polyolefin surface that is more receptive toconventional adhesives. However, such pretreatment adds significant costto a finished assembly and can reduce the economic incentive to usepolyethylene or polypropylene in place of more expensive plastics.Further, some surface treatment procedures, e.g., corona discharge, areonly applicable to thin, flat surfaces and cannot be used in manyexisting applications.

An adhesive which strongly bonds untreated polyethylene, polypropylene,and ethylene-propylene copolymers would represent a significantachievement and present opportunities to not only market a new family ofadhesives, but also open many new markets for such polyolefins in theareas of automobiles, appliances, fabrics, etc.

Compatibility of adhesive and substrate is critical if a strong bond isto be formed. An estimate of compatibility can be obtained from thesolubility parameters (δ) and critical surface tensions (γ_(c)) of thematerials of interest. Generally, a good correlation exists betweensolubility parameter and surface tension for polymers. To form a strongbond, the adhesive should readily wet the surface of the substrate.Polyethylene and polypropylene have γ_(c) values of 31 and 29 dynes/cmand δ values of 7.7-9.2, while typical adhesives have considerablyhigher values so little spreading and wetting occurs, giving pooradhesion using these adhesives.

In addition to wetting, the bond between adhesive and substrate will bestrong if there is a decrease in the free energy as a result ofcombining the two. The free energy change will be negative if the heatof mixing, which is positive for most nonpolar and moderately polarpairs, is small. Since the square of the difference of the solubilityparameters is proportional to the heat of mixing, it is highly desirablethat the solubility parameters for adhesive and substrate beapproximately equal.

It follows from the above that poly(vinylmethylether), PVME, is apotentially attractive component in an adhesive formulated to bond topolyolefin surfaces. The critical surface tension of PVME is 29 dynes/cmand the solubility parameter is in the range 8.5-12.7. Comparison ofthese values with those of polyethylene and polypropylene given abovesuggests that PVME can wet the polyolefin surface and that the heat ofmixing will be small. Both points suggest that PVME could be useful inpolyolefin hot-melt adhesives to form strong bonds between thepolyolefin and various substrates.

Poly(vinylmethylether) also possesses several other interestingproperties that are relevant to its use in adhesive formulations. Whileatactic, isotactic, and syndiotactic forms of the polymer are known, itis the atactic (amorphous) polymer that is of greatest interest inadhesives. This amorphous material is a very viscous resin (typicalnumber average molecular weight in the neighborhood of 5,000-100,000)and it has a wide solubility range, e.g., it is soluble in water, aswell as organic solvents like toluene. This property may be exploited byusing PVME as a compatibilizing agent for dissimilar adhesivecomponents. The hydrophilicity of PVME suggests that surface water andmoisture should not significantly interfere with bonding. The presenceof pendant, polar ether groups provides sites for favorable interactionwith other adhesive components and polymer surfaces.

The literature describing the bonding of polyolefins is extensive.Substrate surface treatment and adhesive formulation are the two generalapproaches the patent literature has taken to improve adherence. In thelatter art both hot-melt and pressure-sensitive adhesives are taught.The literature teaching the use of poly(vinylalkylether) as an adhesivecomponent is also broad. For example, a hot-melt adhesive containingpoly(vinylmethylether) used to laminate such materials as Kraft paper,burlap, cellophane, cellulose, glass, iron and tin is taught in U.S.Pat. No. 2,970,974.

Conventional adhesives that contain a pitch and a poly(vinylalkylether)fluidized by a solvent, which are considered to operate synergistically,are taught as useful to bind polyolefins in U.S. Pat. No. 3,409,498. Thepatent further relates that although a broad range of pitch sourcesproduce a suitable adhesive, "Asphalts and other bituminous substancesdo not produce the same adhesive effects . . . ", which quotationappears at column 3, lines 15-17. Poly(vinylmethylether) is specificallytaught as useful in the patent.

Hot-melt, pressure sensitive adhesive compositions consisting of aprimary polymer which is a solid, homogenous and essentially randomcopolymer of styrene and isobutylene and a secondary polymer which interalia, can be a poly(vinylalkyl ether) are disclosed in U.S. Pat. No.3,644,252. The Examples teach their use for adhering polyester.

Now it has been found that by combining poly(vinylmethylether) with athermoplastic resin and, optionally, a tackifier resin, hot-meltadhesives for polyethylene, polypropylene, and ethylene-propylenecopolymers can be formed which bond these substrates strongly and inwhich the adhesive strength of the bond between adhesive and substrateis generally greater than the cohesive strength of the adhesive.

BRIEF DESCRIPTION OF THE INVENTION

Described herein are hot-melt adhesive compositions useful for bindingpolyolefins comprising substantially amorphous poly(vinylmethylether)and at least 10 percent by weight of a thermoplastic resin selected fromthe group consisting of amorphous C₂ to C₆ polyolefins and copolymersthereof, an ethylene-vinylacetate copolymer, low density polyethylene,polystyrene and block copolymers thereof with isoprene and1,3-butadiene, and ethylene-alkylacrylate copolymers. In another aspectof the invention, such hot-melt adhesive compositions contain inaddition a tackifier resin selected from the group consisting of terpeneresins, terpene-phenol resins, coumarone-indene resins, aliphatic andaromatic petroleum resins, hydrogenated petroleum resins, resins made bycopolymerization of pure aromatic monomers, a wood rosin and wood rosinesters. In still another aspect, the invention includes bondedstructures comprising such hot-melt adhesives and a solid substrateselected from the group consisting of high density polyethylene, lowdensity polyethylene, polypropylene, ethylene-propylene copolymers,polymethylpentene, polycarbonate, latex-backed carpet,polyethylene-backed carpet, high impact polystyrene, galvanized steel,carbon steel, poly(2,6-dimethylphenylene oxide) and blends thereof withpolystyrene, and a copolymer of acrylonitrile, butadiene and styrene.

DETAILED DESCRIPTION OF THE INVENTION

The hot-melt adhesives of this invention contain at least twocomponents. The first component is a poly(vinylalkylether), preferably apoly(vinylmethylether), and more particularly, a substantially amorphouspoly(vinylmethylether), and the second component is a base resin, athermoplastic resin selected from the group consisting of C₂ to C₆polyolefins and copolymers thereof, such as the amorphous polypropylenePolytac R-1000 made by Crowley Chemical Co., an ethylene-vinylacetatecopolymer such as an Ultrathene made by Quantum, a low densitypolyethylene (PE) such as a Petrothene made by Quantum, polystyrene andblock copolymers thereof with isoprene and 1,3-butadiene such as Kraton1107 made by Shell Chemical Co. and Stereon 840 A made by Firestone andhydrogenated variants (soft block) of such block copolymers, and anethylene-alkylacrylate copolymer such as DPD seriesethylene-ethylacrylate copolymer made by Union Carbide Co. Morepreferably, the second component is selected from the group consistingof an amorphous polypropylene (PP), such as Polytac R-1000, amorphouspolypropylene to which is added less than about 20 weight percent ofcrystalline polypropylene, an ethylene-vinylacetate copolymer such as anUltrathene, or a block styrene/isoprene or block styrene/1,3-butadienecopolymer such Kraton 1107 or Stereon 840A.

Preferably, the amount of thermoplastic resin in a two component ormulticomponent adhesive composition is generally at least about 10percent by weight of the total composition, more preferably, more thanabout 15 percent by weight and, most preferably, more than about 20percent by weight of the total composition. In the case where apolystyrene block copolymer is employed as the thermoplastic resin, theamount of resin is at least about 15 percent by weight, and morepreferably at least about 20 weight percent of the weight of the totaladhesive composition. Where an amorphous polyolefin is the thermoplasticresin, the amount of resin is preferably about 50 weight percent, andmore preferably about 75 weight percent, of the total adhesivecomposition.

Usefully, the hot-melt adhesive contains a third component which is atackifier resin. The amount of tackifier resin as a percent of the totaladhesive is at least about 5 weight percent of the total adhesivecomposition, more preferably, at least about 10 weight percent, and mostpreferably, at least about 20 weight percent of the total adhesivecomposition.

In addition, the adhesive composition can contain a fourth componentwhich is a wax or oil extender. Paraffin waxes such as Shellwax 200, 300and 650 and Shellmax 400 and 500 are made by Shell Chemical Company.Other wax extenders include BE Square 175 and 195 made by Petrolite,Polywax 500 and 2000 also made by Petrolite, and Epolene C-10 and C-17made by Eastman Chemical Company. Oil extenders include Shellflex 371made by Shell Chemical Company, Kaydol made by Witco Chemical Companyand a Tuflo oil made by Mobile Chemical Company. The amount of extendercan run between about 10 weight percent and about 70 weight percent ofthe total adhesive composition. More preferably, the amount of wax oroil extender used is between about 20 and about 60 weight percent of thetotal adhesive composition.

In general, the amount of poly(vinylmethylether) in the hot-meltadhesive is at least about 10 weight percent of the total adhesivecomposition, and more preferably, at least about 15 percent of the totaladhesive composition.

The poly(vinylalkylethers) which may be employed are polymers which areliquids or semi-solids at room temperature and are characterized byhaving an inherent viscosity in chloroform within the range of about 0.2to about 3.0. Preferred is a poly(vinylmethylether) such as GantrezM-154 which is a product of GAF, Inc.

The compositions of this invention comprise, on the one hand, acombination of a poly(vinylalkylether) and a thermoplastic resin and, onthe other hand, such combinations additionally containing a tackifierresin selected from the group consisting of terpene resins,terpene-phenol resins, coumarone-indene resins, aliphatic and aromaticpetroleum resins, hydrogenated petroleum resins, resins made bycopolymerization of pure aromatic monomers, naturally occurring gum andwood rosins and their synthetic derivatives such as esters. Thetackifier resin according to the present invention advantageouslyimparts hot tack, substrate wetting, and bond strength to the substratewhile the hot-melt composition is being applied to the substrate.

The tackifier resins contemplated in the present invention are solidcompounds having a softening point above about 75° C. Included withinthis category of materials are the following substances with theirapproximate softening points (by the ring and ball method):

    ______________________________________                                                             Softening Pt.                                            Substance            (°C.)                                             ______________________________________                                        Wood rosin           80                                                       Gum rosin            83                                                       Rosin esters derived from either                                              gum or wood rosin such as:                                                    Glycerol esters (ester gums)                                                                       90                                                       Pentaerythritol esters                                                                             115                                                      Hydrogenated rosin   75                                                       Polymerized rosin    100                                                      Disproportionated rosin                                                                            80                                                       Polyhydric alcohol derivatives of                                             hydrogenated rosin, e.g.:                                                     Glycerol derivatives 85                                                       Polyhydroalcohol derivatives of                                               polymerized rosin, e.g.:                                                      Ethylene glycol ester                                                                              82                                                       Glycerol ester       110                                                      Oxidized rosins      105                                                      Hydrogenated oxidized rosin esters                                            of oxidized rosin and the like.                                               ______________________________________                                    

Any of the common commercial grades of wood or gum rosin may be employedranging from the "X" and water white grades to the darkest grades (e.g.,D-grade). The impurities in the latter which give rise to the color bodyformation have no significant effect upon the usefulness of thecompositions of this invention.

The tackifier resin is advantageously an alpha-methylstyrene, a rosin,or a terpene resin of the alpha-pinene, beta-pinene and d-limonenetypes. Preferably, the tackifying resin has a ring and ball softeningpoint of 85° to 150° C., more preferably 85° to 135° C., a Gardner colorof 2 to 10, and a flashpoint greater than 230° C.

A preferred alpha-methylstyrene tackifier resin of the present inventionis commercially available under the trademark "Kristalex 1120.""Kristalex 1120" is a water white, color stable, nonpolar, thermoplastichydrocarbon resin that is a copolymer of styrene andalpha-methylstyrene, and has a ring and ball softening point of 120° C.,a specific gravity of 1.07, and a flashpoint of 232° C.

A preferred rosin type tackifier resin, commercially available under thetrademark "Sylvatac 140," is a polymerized rosin with a ring and ballsoftening point of 140° C., a Gardner color of 10, an acid number of135, a saponification number of 140 and a specific gravity of 1.08.

Suitable hydrocarbon tackifier resins can be a hydrocarbon resin such asDAC-B hydrocarbon resin prepared according to the process disclosed inU.S. Pat. No. 3,701,760 as well as other hydrocarbon resins,polyterpenes or synthetic polyterpenes, and the like. One suchhydrocarbon tackifying resin is a hydrocarbon resin having a softeningpoint of about 100° C. and available commercially as Eastotac H-100 fromEastman Chemical Products, Inc. Other hydrocarbon tackifying resins canbe prepared by the polymerization of monomers consisting primarily ofolefins and diolefins and include, for example, the residual by-productmonomers resulting from the manufacture of isoprene. These hydrocarbontackifier resins typically exhibit a ring and ball softening point offrom about 80° C. to about 135° C.; an acid number of from about 0-2; asaponification value of less than about 1; and an iodine value of fromabout 30 to 100. Examples of such commercially available resins of thistype are "Wingtack" 95 and "Wingtack" 115 tackifying resins sold by theGoodyear Tire and Rubber Company, the Sta-Tac and Betaprene A or Hresins sold by the Reichold Chemical Corporation, Arkon resins sold byArakawa Forest Chemical Industries, and Escorez resins sold by ExxonChemical Co.

Additional suitable resins are the terpene polymers such as thepolymeric, resinous materials obtained by polymerization and/orcopolymerization of terpene hydrocarbons such as the alicyclic,monocyclic, and bicyclic monoterpenes and their mixtures, includingallo-ocimene, carene, isomerized pinene, pinene, dipentene, terpinene,terpinolene, limonene, turpentine, a terpene cut or fraction, andvarious other terpenes. Particularly useful starting materials areterpene mixtures containing at least 20 percent beta-pinene and/orlimonene or dipentene (racemic limonene), and the "sulfate turpentine"obtained as a by-product in the sulfate pulping process. Commerciallyavailable resins of the terpene type include the Zonarez terpeneB-Series, the 7000 Series resins from Arizona Chemical Corp., and Nirezresins from Reichold Chemical Corp. Typical properties reported for theZonarez terpene resins include ring and ball softening point of about55° to 125° C. (ASTM E-28-67), color of 2 to 3 (Gardner 1963, 50% inheptane), acid number of less than 1 (ASTM D465-59), saponificationnumber of less than 1 (ASTM D464-59), and specific gravity at 25° C. of0.96 to 0.99 (ASTM D1963-61).

By virtue, therefore, of the combination of the poly(vinylmethylether)with the hydrocarbon and tackifier resins, it is possible to providehot-melt adhesive compositions which give excellent adhesive bondsquickly, which bonds are not subject to deterioration when exposed toconditions of high humidity or water immersion or the like.

Other ingredients may be included in the hot-melt composition accordingto the present invention.

For example, a silane adhesion promoter can be advantageously included.A polyunsaturated polyalkoxysilane, 50% in siloxane, is commerciallyavailable under the trademark "CPSO78 6S". Other silanes may also beused as adhesion promoters.

Anionic and nonionic wetting agents that are stable at normal hot-meltapplication temperatures may also be used. An example of a suitablewetting agent is sodium dioctyl sulfosuccinate.

An antioxidant is also advantageously included to control the aging ofthe composition. A preferred antioxidant is the3,5-di-tert-butyl-4-hydroxyhydrocinamic acid triester of1,3,5-tris-(2-hydroxyethyl)-s-triazine-2,4,6-(1H,3H,5H) trione with amolecular weight of 1042 commercially available under the trademark"Vanox SKT." Antioxidants that are also effective include, for example,tris(di-t-butyl-p-hydroxybenzyl)-trimethylbenzene (Lonox 330), alkylatedbisphenol (Naugawhite), zinc dibutyl dithiocarbamate (Butyl Zimate), and4,4'-methylene bis(2,6-di-tert-butylphenol) (Ethyl 702),tetrakis[methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate) methane](Irganox 1010), lauryl stearyl thiodipropionate (Plastanox 1212), anddilauryl 3,3'-thiodipropionate (Plastanox LTDP),2,6-di-tert-butyl-p-cresol (BHT) and the like. Such materials, ifpresent, are used in relatively small amounts as may be understood byone skilled in the art.

Additives such as nucleating agents, pigments, colorants, fillers,solvents, and the like can also be added to the adhesive compositions ofthe present invention.

An effective amount of crystalline polypropylene, for example, up toabout 15 weight percent of the amorphous polypropylene used may beincluded in the thermoplastic resin portion of the hot-melt compositionto improve the cohesive properties of hot-melts made using amorphouspolypropylene.

The adhesive compositions of this invention are prepared by blendingtogether the adhesive components in the melt at a temperature of about160° C. to about 200° C. until a homogeneous mixture is obtained.Various methods of blending materials of this type are known to the artand any method that produces a homogeneous mixture is satisfactory.These components blend easily in the melt and a heated vessel equippedwith a stirrer is all that is required. For example, a Cowles stirrerprovides effective mixing for preparing these compositions. Solventssuch as hexane, heptane, mineral spirits, xylene, toluene, benzene,chlorinated hydrocarbons, etc., are not needed to prepare thecompositions of this invention; however, they can be used if desired.

The adhesive compositions of this invention, which are essentially 100percent solids, have a melt viscosity in the range of about 100 to about150,000 centipoise at 177° C.

The adhesive compositions of this invention can be used for any use towhich adhesives have been put as can be understood by one skilled in theart. While use for hot-melt adhesives is preferred, the compositionsalso may be used in water-borne, pressure-sensitive adhesives. Inparticular, the inventive compositions are able to strongly bondpolyolefins and their copolymers, preferred polyolefins arepolyethylene, polypropylene, and ethylene-propylene copolymers, tothemselves and to other substrates such that failure of the interfacialbond is generally cohesive rather than interfacial. Substrates which areuseful to bond to the polyolefin or polyolefin copolymer include highdensity polyethylene, low density polyethylene, polypropylene,ethylene-propylene copolymers, polymethyl-pentene, polycarbonate,latex-backed carpet, polyethylene-backed carpet, high impactpolystyrene, galvanized steel, carbon steel, aluminum. paper, glass,polyethylene terephthalate, poly(2,6-dimethylphenylene oxide) and blendsthereof with polystyrene, a copolymer of acetonitrile, butadiene,styrene, and the like. More preferably, substrates such as high densityand low density polyethylene, polypropylene, ethylene-propylenecopolymer, polycarbonate, latex-backed carpet and polyethylene-backedcarpet, aluminum, paper, and polyethylene terephthalate are used.

The following Examples will serve to illustrate certain specificembodiments of the herein disclosed invention. These Examples shouldnot, however, be construed as limiting the scope of the novel invention,as there are many variations which may be made thereon without departingfrom the spirit of the disclosed invention, as those of skill in the artwill recognize.

EXAMPLES General Adhesive Strength Testing

Lap shear strength was measured by a test based upon ASTMD-1002-72. Lapshear assemblies were prepared from two 1 in×6 in×1/8 in strips ofspecified substrate (e.g., polypropylene, polyethylene, high impactpolystyrene, etc.). The assembly was prepared by dispensing hot-meltadhesive from an appropriate applicator onto the end of one test stripand then overlapping a second strip on top of the first. The area ofoverlap is one square inch. A 5 lb weight was immediately rolled twiceover the bonded joint. Spacers or a jig are used to set the bondthickness.

Lap shear strength was measured by a tensile test machine, such as anInstron Model 4201 using a tension load cell of 1000 lbs and a crossheadspeed of 2 in/min.

Peel strength was measured by the Pressure Sensitive Tape Council MethodPSTC #1 contained in its 9th edition and last revised in August 1989.

Experimental Adhesive Formulation

A representative hot-melt formulation is listed below and was preparedin the following manner:

50 g poly(vinylmethylether) (Gantrez M-154, 50% water)

25 g polyterpene (Zonarez B-115)

50 g ethylene-vinylacetate copolymer (USI UE 612-04, melt index of 150)

The poly(vinylmethylether) (PVME) was first weighed into a 500 ml resinkettle and then the remaining components were added. The kettle wasplaced overnight in an oven set at 105°-115° C. The oven had a nitrogenpurge allowing the water vapor from the PVME to be removed. The next daythe kettle was removed from the oven and cooled to room temperatureunder a blanket of nitrogen. When cooled, the kettle was equipped with acover, stirring shaft, paddle, Truebore bearing, mechanical stirrer anda nitrogen purge. The kettle was put into a silicone oil bath that wascontrolled by a TIC and TIS control box at 175° C. Stirring began whenthe formulation softened. If a formulation did not blend well, thetemperature was raised to 200° C. Once the formulation was completelyblended, the kettle was raised out of the oil bath and tilted to oneside causing the formulation to flow slowly along the side of thekettle. When the formulation cooled, it was then removed from thekettle.

Adhesives Application to Polypropylene Strips

A small amount of the hot-melt formulation was placed in a Mini-Squirthot-melt glue gun (Slautterback Corporation Model 71026). The gun washeated to 200° C. Using polypropylene sticks wiped once with hexane, thehot-melt was added to a 1 inch square area of the bottom strip. Then thetop strip was placed on top of the hot-melt area and pressed in placewith a 5 kg weight. The thickness of the hot-melt was determined by thesize of the spacer used. The bonded strips were cooled for a few minutesbefore the weight was removed and were cured overnight at roomtemperature.

EXAMPLE 1

Various hot-melt adhesives were made by hot mixing 25 weight percent ofGantrez M-154, an amorphous poly(vinylmethylether) purchased from GAF,Inc., 50 percent by weight of base resin, and 25 weight percent ofZonarez B-115, a tackifier resin purchased from Arizona Chemical Co. Theresults of lap shear strength tests on structures formed by bonding two1 in×6 in×1/8 in polypropylene strips treated with the hot-meltadhesives is shown below.

                  TABLE 1                                                         ______________________________________                                                           Lap shear strength                                                                          Failure                                      Thermoplastic Resin                                                                              (psi)         Mode                                         ______________________________________                                        EVA.sup.1          221           .sup. C.sup.2                                LDPE.sup.3         257           C                                            Amorphous polypropylene.sup.4                                                                    197           C                                            Ethylene-ethylacrylate.sup.5 copolymer                                                           130           C                                            Polystyrene.sup.6  112           C                                            ______________________________________                                         .sup.1 Ethylene-vinylacetate copolymer USI UE 61404 Ultrathene (18%           vinylacetate, 150 melt index) made by Quantum Chemical                        .sup.2 Cohesive bond failure                                                  .sup.3 USI Petrothene NA 596, 150 melt index made by Quantum Chemical.        .sup.4 Polytac R1000 made by Crowley Chemical Co.                             .sup.5 UCC DPD9169 (19% ethylacrylate, 20 melt index) made by Union           Carbide Corp.                                                                 .sup.6 Supplied by Amoco Chemical Co.                                    

COMPARATIVE EXAMPLE 2

Hot-melt adhesives from 50 weight percent ethylene-vinylacetatecopolymer, Ultrathene USI 612-04 (18% vinyl acetate, 150 melt index), 25weight percent of three different poly(vinylalkylether)s, and 25 weightpercent of the polyterpene Zonarez B-115 were made by hot mixing. Theiradhesive properties are set out in Table 2 below.

                  TABLE 2                                                         ______________________________________                                        Effect of Change in Vinylether Polymer Type                                                    Lap shear strength                                                                          Failure                                        Vinylether Polymer                                                                             (psi)         Mode                                           ______________________________________                                        Poly(vinylmethylether)                                                                         221           C                                              Poly(vinylethylether)                                                                           57           C                                              Poly(vinylisobutylether)                                                                       281           .sup. I.sup.1                                  ______________________________________                                         .sup.1 Interfacial bond failure                                          

EXAMPLE 3

Hot-melt adhesives from 25 weight percent Gantrez M-154poly(vinylmethylether), 50 weight percent of low density polyethylene(USI Petrothene NA 596 150 melt index) and 25 weight percent of severaltackifier resins were made by hot mixing. Their adhesive properties areset out in Table 3 below.

                  TABLE 3                                                         ______________________________________                                                                  Lap Shear  Failure                                  Tackifier Resin                                                                         Type            Strength (psi)                                                                           Mode                                     ______________________________________                                        Zonarez B-115.sup.1                                                                     Poly(β-pinene)                                                                           256        C                                        Zonarez B-125.sup.1                                                                     Poly(β-pinene)                                                                           282        C                                        Zonester 100.sup.1                                                                      Tall Oil Rosin Ester                                                                          137        C                                        Nevtac 115.sup.2                                                                        Synthetic Polyterpene                                                                         217        C                                                  Resin                                                               Nevex 100.sup.2                                                                         Petroleum Hydrocarbon                                                                         100        C                                                  Resin                                                               ______________________________________                                         .sup.1 Made by Arizona Chemical Co.                                           .sup.2 Made by Neville Chemical Co.                                      

EXAMPLE 4

Hot-melt adhesives from 25 weight percent Gantrez M-154poly(vinylmethylether), 50 weight percent of USI UE614-04 Ultratheneethylene-vinylacetate, and 25 weight percent of several tackifier resinswere made by hot mixing. Their adhesive properties are set out in Table4 below.

                  TABLE 4                                                         ______________________________________                                                                  Lap Shear  Failure                                  Tackifier Resin                                                                         Type            Strength (psi)                                                                           Mode                                     ______________________________________                                        Zonarez B-115                                                                           Poly(β-pinene)                                                                           221        .sup. C.sup.1                            Zonarez B-125                                                                           Poly(β-pinene)                                                                           275        C                                        Zonester 100                                                                            Tall Oil Rosin Ester                                                                          192        C                                        Nevtac 115                                                                              Synthetic Polyterpene                                                                         150        C                                                  Resin                                                               Nevex 100 Petroleum Hydrocarbon                                                                         193        .sup. I.sup.2                                      Resin                                                               ______________________________________                                         .sup.1 Cohesive                                                               .sup.2 Interfacial                                                       

EXAMPLE 5

The effect of changing ethylene-vinylacetate (EVA) percentages andpoly(vinylmethylether) (PVME) percentage was evaluated in this Example.No tackifier resin was used. The test data is shown in Table 5 below.

                  TABLE 5                                                         ______________________________________                                        %      %       % VA.sup.3 in                                                                           EVA   Lap Shear                                                                              Failure                               PVME.sup.1                                                                           EVA.sup.2                                                                             the EVA   MI.sup.4                                                                            Strength (psi)                                                                         Mode                                  ______________________________________                                         0     100     28        388   129      I                                     20     80      28        388   145      I                                     33     67      28        388   201      C                                     50     50      28        388    38      C                                      0     100     18        150   108      I                                     25     75      18        150   282      C                                     25     75      18        530   229      C                                     ______________________________________                                         .sup.1 Gantrez M154                                                           .sup.2 A USI Ultrathene                                                       .sup.3 VA is vinyl acetate                                                    .sup.4 MI is melt index                                                  

EXAMPLE 6

The effect of changing the PVME and tackifier resin percentages forhot-melt adhesives containing amorphous polypropylene was evaluated. Thedata is shown in Table 6 below.

                  TABLE 6                                                         ______________________________________                                        %      %          %           Lap Shear                                                                              Failure                                PVME.sup.1                                                                           Polyterpene.sup.2                                                                        Amorphous PP                                                                              Strength (psi)                                                                         Mode                                   ______________________________________                                        25     25         50          197      C                                      35     15         50          64       C                                      30     30         40          160      C                                      35     --         65          69       C                                      30     --         70          74       C                                      ______________________________________                                         .sup.1 Gantrez M154                                                           .sup.2 Zonarex B115                                                      

EXAMPLE 7

The effect of changing the EVA percentage in a hot-melt adhesive madefrom 25 weight percent Gantrez M-154 PVME, 50 weight percent of a USIUltrathene EVA, and 25 weight percent Zonarez B-115 tackifier resin isshown in Table 7 below.

                  TABLE 7                                                         ______________________________________                                        % EVA in % VA in   Melt     Lap Shear Failure                                 Adhesive EVA       Index    Strength (psi)                                                                          Mode                                    ______________________________________                                        50       18        150      221       C                                       50       28        150      121       C                                       50       19        32       112       C                                       .sup. 40.sup.1                                                                         18        150      242       C                                       10       19        2.5                                                        .sup. 30.sup.1                                                                         18        150      108       I/C                                     20       19        2.5                                                        .sup. 30.sup.1                                                                         18        150      119       C                                       20       19        32                                                         .sup. 30.sup.1                                                                         18        530      202       C                                       20       19        2.5                                                        ______________________________________                                         .sup.1 Two different EVAs with the tabulated properties were used for eac     hotmelt adhesive made in this preparation.                               

EXAMPLE 8

Several different hot-melt adhesives were made by hot mixing and used tobond latex-backed carpet to a polypropylene (PP) substrate. The testresults on adhesive strength are shown below in Table 8.

                  TABLE 8                                                         ______________________________________                                                          Load at                                                     Adhesive          Failure                                                     Composition       (psi)     Comments                                          ______________________________________                                        25% PVME/25% Polyterpene.sup.1                                                                  54        Carpet.sup.3 Failed                               50% Amorphous PP            Before Bond                                       (Polytac R-1000).sup.2                                                        25% PVME/25% Polyterpene                                                                        .sup. 56.sup.4                                                                          Carpet Failed                                     50% Amorphous PP            Before Bond                                       (Polytac R-1000)                                                              25% PVME/25% Polyterpene                                                                        38        Cohesive Bond                                     50% Amorphous PP            Failure                                           (Polytac R-500).sup.2                                                         30% PVME          39        Cohesive Bond                                     70% Amorphous PP            Failure                                           (Polytack R-1000)                                                             35% PVME          42        Cohesive Bond                                     65% Amorphous PP            Failure                                           (Polytac R-1000)                                                              ______________________________________                                         .sup.1 Zonarez B115                                                           .sup.2 Polytac R1000 and R500 are amorphous polypropylenes supplied by        Crowley Chemical Co.                                                          .sup.3 The latexbonded carpet substrate was supplied by Chrysler Corp.        .sup.4 Structure aged 1 week at 175° F. under a 0.11 psi load.    

COMPARATIVE EXAMPLE 9

A hot-melt adhesive using 50 weight percent amorphous polypropylene(Polytac R-1000), 25 weight percent PVME, and 25 weight percent ZonarezB-115 tackifier resin was made by hot mixing and used to bondpolyethylene-backed carpet made by Magee Carpet Co. to a polypropylene(PP) substrate. The test results together with results using twocommercial hot-melt adhesives are shown in Table 9 below.

                  TABLE 9                                                         ______________________________________                                                     Load at                                                          Adhesive     Failure                                                          Composition  (psi)    Comments                                                ______________________________________                                        25% PVME/    40       PE Backing Failed 3 Times                               25% Polyterpene       More Frequently Than The                                50% Amorphous PP.sup.1                                                                              Adhesive Bond                                           100% Amorphous PP.sup.1                                                                    33       Interfacial Bond Failure                                Polyolefin Base.sup.2                                                                      37       Interfacial Bond Failure                                ______________________________________                                         .sup.1 This amorphous polypropylene supplied by Baychem International,        Inc. as KTAC 200A.                                                            .sup.2 Jetmelt 3797, a polyolefinbased commercial hotmelt adhesive            supplied by 3M.                                                          

EXAMPLE 10

A styrene isoprene block copolymer based hot-melt adhesive was preparedfrom:

10 g poly(vinylmethylether)

20 g petroleum oil (Shellflex 371)

20 g styrene isoprene block copolymer (Kraton 1107)

50 g polyterpene (Zonatac 105 Lite)

1 g antioxidants (0.5 g Irganox 1010 and 0.5 g Butyl Zimate) by hotmixing.

Polyterpene, petroleum oil and antioxidants were added into a tin can.The can was warmed to 165°-170° C. while purging with nitrogen. Themixture was stirred until all ingredients were completely blended. Thestyrene isoprene block copolymer was then added to the formulation andmixed until blended. Finally, poly(vinylmethylether) was added andstirred until the formulation had again blended.

A control adhesive without PVME was also made by hot mixing 20 wt %Kraton 1107, 20 wt % Shellflex 371 and 60 wt % Zonatac 105 Lite in aprocess similar to that used above for the styrene isoprene blockcopolymer bond hot-melt adhesive. Lap shear strength measurements onpolypropylene strips bound by the two hot-melt adhesives give values of62 psi for the control adhesive and 69 for the adhesive modified byPVME.

Peel strength tests were also performed on structures formed by a twostep process. First a 3 mil layer of the control or PVME-modifiedadhesive were cast onto the uncoated side of Kromekote paper using aheated drawdown bar. This paper was then cut into 1 in×5 in strips andbonded to the substrates listed in Table 10 below.

                  TABLE 10                                                        ______________________________________                                                                   PVME Modified                                      Substrate    Peel Strength (pli)                                                                         (pli)                                              ______________________________________                                        polyethylene 1.5 mil                                                                       fiber tear and PE                                                                           fiber tear and PE                                  thickness    deformation   deformation                                        polypropylene 1.5 mil                                                                      fiber tear    fiber tear                                         thickness, corona                                                             treated                                                                       aluminum foil 1 mil                                                                        fiber tear    fiber tear and                                     thickness                  aluminum failure                                   glass, 10 mil                                                                              fiber tear    9.5, cohesive                                      ______________________________________                                         pli = pounds per linear inch                                             

EXAMPLE 11

A styrene butadiene block copolymer based hot-melt adhesive was preparedfrom:

10 g poly(vinylmethylether)

28 g petroleum oil (Shellflex 371)

16 g styrene butadiene block copolymer (Stereon 840A)

45 g polyterpene (Zonatac 105 Lite)

1 g antioxidants (0.5 g Irganox 1010 and 0.5 g Butyl Zimate) by hotmixing.

Polyterpene, petroleum oil and antioxidants were added into a tin can.The can was warmed to 165°-170° C. while purging with nitrogen. Themixture was stirred until all ingredients were completely blended. Thestyrene butadiene block copolymer was then added to the formulation andmixed until blended. Finally, poly(vinylmethylether) was added andstirred until the formulation had again blended.

For comparison purposes, a control adhesive without the PVME was made.The control adhesive was made by hot mixing 16 wt % Stereon 840,28 wt %Shellflex 371 and 55 wt % Zonatac 105 Lite.

Peel strength tests were also performed on structures formed by a twostep process. First a 3 mil layer of the control or PVME-modifiedadhesive were cast onto the uncoated side of Kromekote paper using aheated drawdown bar. This paper was then cut into 1 in×5 in strips andbonded to the substrates listed in Table 11 below.

                  TABLE 11                                                        ______________________________________                                                                    PVME Modified                                                   Control Strength                                                                            Peel Strength                                     Substrate     (pli).sup.1   (pli)                                             ______________________________________                                        polyethylene 1.5 mil                                                                        brittle peel, variable                                                                      fiber tear and PE                                 thickness     strength      deformation                                       polypropylene 1.5 mil,                                                                      3.5, fiber tear                                                                             fiber tear                                        thickness corona treated                                                      aluminum foil 1 mil                                                                         4.8, cohesive 5.1, cohesive                                     thickness                                                                     glass, 10 mil thickness                                                                     fiber tear    8.1, cohesive                                     ______________________________________                                         .sup.1 pli = pounds per linear inch                                      

EXAMPLE 12

The effect of PVME proportion on the properties of the adhesive wasevaluated for adhesives containing 33 parts ethylene-vinyl acetate(ELVAX 250), 33 parts Shellwax 300 and 33 parts of Wingtack Plus. Theresults of peel tests on the adhesives bonded to various substrates areshown below in Table 12.

                  TABLE 12                                                        ______________________________________                                              Peel Strength.sup.1                                                                          Peel Strength.sup.1                                      PVME  Polypropylene  Polyethylene                                                                              Peel Strength.sup.1                          (%)   Treated  Untreated (Untreated)                                                                             Aluminum                                   ______________________________________                                         0     20       20       25        200 SS.sup.4                               10     35       40       60 B.sup.3                                                                              300 SS                                     20    100 B    150 B     70 B      250 S.sup.5                                30    120 SS   250 SS    60 SS     300 S                                      ______________________________________                                         .sup.1 units of pounds per linear inch                                        .sup.2 treated by corona discharge                                            .sup.3 brittle                                                                .sup.4 soft                                                                   .sup.5 semi-soft                                                         

COMPARATIVE EXAMPLE 13

A control adhesive made from 65 g of Rexene 2730 and 35 g of WingtackPlus and a PVME adhesive made from 65 g of Rexene 2730, 20 g of WingtackPlus, and 15 g of PVME were applied to a number of substrates andstrength tested. The results are set out below in Table 13.

                  TABLE 13                                                        ______________________________________                                                  Control Adhesive Peel                                                                         PVME Adhesive Peel                                  Substrate.sup.1                                                                         Strength (pli)  Strength (pli)                                      ______________________________________                                        Polyethylene                                                                            PE deformed (4.3)                                                                             PE deformed (4.5)                                   Polypropylene                                                                           fiber tear      fiber tear                                          Mylar     fiber tear      3.7 - soft peel                                     cohesive                                                                      EVA       fiber tear      fiber tear                                          Aluminum  3.5 - soft peel 4.4 - soft peel                                     cohesive                                                                      Kraft Paper                                                                             1.8 - soft peel fiber tear (Kraft)                                  cohesive                                                                      Glass     fiber tear      fiber tear                                          ______________________________________                                         .sup.1 All bonds were made between the uncoated side of Kromekote and the     substrate listed.                                                        

COMPARATIVE EXAMPLE 14

A control adhesive made from 33 g of Elvax 250, 23 g of Shellwax 300, 10g of Castorwax, and 33 g of Wingtack Plus and PVME adhesive made from 33g of Elvax 250, 23 g of Shellwax 300, 10 g of Castorwax, 23 g ofWingtack Plus, and 10 g of PVME was applied to a number of substratesand Kronekote (Krone) paper and strength tested. The results are set outbelow in Table 14.

                  TABLE 14                                                        ______________________________________                                                Control Adhesive Peel                                                                          PVME Adhesive Peel                                   Substrate.sup.1                                                                       Strength (pli)   Strength (pli)                                       ______________________________________                                        Poly-   0.2 - brittle @PE.sup.2                                                                        1.1 - semi-brittle @PE.sup.2                         ethylene                                                                      Poly-   0.1 - semi-brittle @PP.sup.3                                                                   0.2 - semi-soft @PP                                  propylene                                                                     Mylar   0.0 - brittle @Mylar.sup.4                                                                     0.1 - brittle @Mylar                                 EVA     0.2 - semi-brittle @EVA.sup.5                                                                  0.5 - semi-brittle @EVA                              Aluminum                                                                              0.4 - semi-soft @Alum..sup.6                                                                   0.5 - semi-soft @Alum.                               Kraft   fiber tear (Krome)                                                                             fiber tear (Kraft)                                   Paper                                                                         Glass   fiber tear       fiber tear                                           ______________________________________                                         .sup.1 All bonds were made between the uncoated side of Kromekote paper       and the substrate listed.                                                     .sup.2 Type of bond failure at the adhesive polyethylene interface.           .sup.3 Adhesive-polypropylene interface                                       .sup.4 Adhesive-mylar interface                                               .sup.5 Adhesive-EVA interface                                                 .sup.6 Adhesive-aluminum interface                                       

What is claimed is:
 1. A hot-melt adhesive composition useful forbinding polyethylene, polypropylene, and ethylene-propylene copolymerscomprising at least about 10 weight percent of substantially amorphouspoly(vinylmethylether) and at least about 10 percent by weight of athermoplastic resin which is an ethylene-vinylacetate copolymer.
 2. Thecomposition of claim 1 which contains a tackifier resin selected fromthe group consisting of terpene resins, terpene-phenol resins,coumarone-indene resins, aliphatic and aromatic petroleum resins,hydrogenated petroleum resins, resins made by copolymerization of purearomatic monomers, a wood rosin, and wood rosin esters.
 3. A bondedstructure comprising the adhesive of claim 1 and a solid substrateselected from the group consisting of high density polyethylene, lowdensity polyethylene, polypropylene, ethylene-propylene copolymers,polymethylpentene, latex-backed carpet, polyethylene-backed carpet, highimpact polystyrene, polyethylene terephthalate,poly(2,6-dimethyl-phenylene oxide) and blends thereof with polystyrene,and a copolymer of acrylonitrile, butadiene and styrene.
 4. A bondedstructure comprising the adhesive of claim 2 and a solid substrateselected from the group consisting of high density polyethylene, lowdensity polyethylene, polypropylene, ethylene-propylene copolymers,polymethylpentene, latex-backed carpet, polyethylene-backed carpet, highimpact polystyrene, polyethylene terephthalate,poly(2,6-dimethyl-phenylene oxide) and blends thereof with polystyrene,and a copolymer of acrylonitrile, butadiene and styrene.
 5. A bondedstructure comprising the adhesive of claim 2 and a polyethylenesubstrate.
 6. A bonded structure comprising the adhesive of claim 2 anda polypropylene substrate.
 7. A bonded structure comprising the adhesiveof claim 2 and an ethylene-propylene copolymer substrate.